Electromagnetic coil



ELECTROMAGNET IC COIL Filed Sept. 7, 1929 ENE INVENTOR. ROBERT STTl/EA/S BY jfi g jmw ATTORNEYS Patented Jan. 31, 1933 p UNITED STATES PATENT OFFICE ROBERT E. STEVENS, OF LABCHMONT, NEW YORK I ELECTROMAGNETIC COIL Application filed September 7, 1929. Serial No. 391,021. The invention relates to electro-magnetic so that in semi or complete darkness, said recoils and has for its object to provide acoil sistance will be at its highest point and thus, of the indicated class which will operate aufor instance, will bring about the closing of a tomatically in response to variations in the suitable contact means whereby an electric intensity of light to which the coil is exposed. current from a suitable source is permitted ther more specific objects will appear from to freely pass over a predetermined circuit. the description hereinafter, and the features As the darkness changes to light or the light of novelty will be pointed out in the claims. increases in intensity beyond the point at In the accompanying drawing, which which the conductor 13 is of increased resistshows an example of the invention without ance, its inherent characteristics will cause 9 defining its limits, Fig. 1 is a perspective view the resistance to be correspondingly decreased of the novel coil; Fig. 2 is a longitudinal secso that the aforesaid contact means is opertion thereof, and Fig. 3 is a diagrammatic ated in a manner to arrest the passage of view illustrating an installation for which said electric current over said circuit. With the coil is particularly adapted. the arrangement set forth electric current As shown in the drawing, the novel electrofrom the aforesaid suitable source may acmagnetic coil consists of the customary soft cordingly be cut off from the wire conductor iron core 10, and the conventional insulated 11 when the light to which the coil is exposed wire conductor 11 which is wound about said turns to darkness or its intensity is otherwise core 10 to form the conventional spool, as reduced, so that the core 10 may be de-magq shown in Figs. 1 and 2. The novel coil furnetized during periods of darkness or semither includes a cover 12 which encloses the darkness. On the other hand when the light conductor 11 and is made of any suitable into which the coil is exposed is sufficiently insulating material, said cover 12 being fixed in tense the resistance developed in the wire place in any convenient way. conductor 13 will be reduced sufficiently to 'Upon its exterior the coil is provided with permit the core 10 to be magnetized and re- E a conductor element, for instance selenium, main magnetically active during periods of the electrical conductivity of which varies in light.

accordance with changes in light,and which is The novel light-sensitive coil may be used connected in series with the wire conductor in a variety of ways for automatic control 11, and is located in insulated relation therein accordance with light variations, and beto. In the illustrated example, the aforesaid cause of its compactness is easily installed conductor element extends exteriorly about in spaces of small dimensions. In all instalthe insulating cover 12 and consists of a seclations the coil is efficient and reliable and 0nd wire conductor 13 of selenium wound eX- does away with the necessity for a plurality y about Said insulating COVQI 12 and of separate units which heretofore have been connected in series with the first named wire f d necessary in light iti t lli conductor 11, as shown. The variable re- Svstems.

sistance element or wire conductor 13 in the The novel coil is particularly adapted for illustrated example, thus comprises the outer automatically controlling the circuits of elec layer of h electm'magnetlc. 9 and p trio lights in a manner to switch on such sesses the inherent characteristic of having lights automatically when a Condition of its electrical conductivity responsive to l i s. m l-darkness 1S reached 1n the changes 1n any llflllt to which it may be exdarl me i or Se 5 posed. That is to say, in daylight or other lilclmty of the C011 and to Swltch light of corresponding or greater intensity, hghts when darknss C11a ngeS tO the conductor 13 when composed of selenium Shown dlaglzammatlcanydn 3 the or its equivalent will develop an electrical @0 y accordlngly efiiclently used f resistance which increases as the intensity automatically switching on the parking of the light to which it is exposed decreases, lights of an automobile when the latter re- .ventional battery 20 or other source of elec tricity. The opposite pole of said battery 20 or its equivalent is connected by means of a wire 21 with a contact 22 whichcooperates with a contact 23 carried by the armature lever 16 to control the circuit in which the lamp 14 is located; for purposes of adjustment the contact 23 may consist of a screw mounted in threaded engagement with said lever 16.

In addition to the above the wire conductor 11 of the electro-magnetic coil is connected with one pole of the battery 20 for instance by means of a wire 24: cut in on the wire 17 at a point between the switch 18 and the lamp 14. The light sensitive wire conductor 13 or its equivalent is, in turn,

connected with the other pole of said battery 20 for instance, by means of a wire 25 cut in on the wire 21 to complete the circuit. It will of course be understood that the circuit may be otherwise arranged to produce the same or equivalent results. A coil spring 26 may be provided for returning the armature lever 16 to the position in which, in Fig. 3 of the illustrated example, the contacts 22 and 23 are in engagement with each other. In addition the customary adjustable stop 27 may be provided for arresting the movement of the armature lever 16 by the action of the spring 26; in the form shown in the drawing the stop 27 consists of a suitable screw mounted in a stationary support 28 as shown in Fig. 3. a

In practice where an automobile equipped with the novel control means is parked at a time of the day when darkness approaches,

and it is desired to have the parking light or lights automatically switched on at the proper time, the switch 18 is closed to bring the battery 20 into closed circuit with the lamp 14c and the novel control coil.

As long as sufficient daylight remains in the vicinity of the parked automobile, the light effective upon the conductor 13 will decrease the resistance therein sufliciently to permit the passage of the current from the battery 20 to the coil conductor 11. The core 10 accordingly is brought to a magnetized condition and the armature lever 16 is attracted by the core 10 and the contacts 22 and 23 are separated so that the light circuit is broken. When a condition of darkness is reached the resistance in the conductor 13 will be gradually increased to a point at which obstruction to passage of the battery current to the coil conductor 11 is developed, so that the core 10 gradually loses its magnetism and the tension of the spring 26 is finally sufficient to move the armature lever 16 away from the said core 10. As soon as this occurs the contact 23 will be brought into engagement with the contact 22 to close the lamp circuit, so that current will pass from the battery 20 to the lamp 1 1 to electrically energize the same. The entire system may be thrown out of operation at will by simply opening the switch 18 which, in practice, will be located within easy reach of the chauffeur or other operator of the vehicle. Obviously if the latter is permitted toremain parked until darkness changes to daylight and the switch 18 remains in its closed po sition, the daylight, as soon as it reaches the required intensity, will again decrease the resistance in the conductor 13 whereby the passage of the current from the battery 20 to the conductor 11 will again be permitted. At this point the core will be again magnetized and the armature lever 16 will be attracted by the core 10 and move the contact 23 away from the contact 22 and thereby break the circuit in which the lamp 14 is located; as a result the lamp will be extinguished.

From'the above it will be clear that the parking lights of an automobile, or the electric lights of any other system, may be automatically switched on and oli in exact accordance with existing or developed conditions of light and darkness without the assistance or supervision of any human agency other than the operation of closing the switch 18 if it forms a part of the installation. The novel device may be used with equal efficiency for the corresponding control of other devices, and it is accordingly to be understood that the diagrammatic illustration of Fig. 3 is only an example of its utility.

In any case the device is reliable in its operation and control and because of its compactness may be embodied in an automobile or other desired unit or in any place in an inconspicuous manner and without affecting the appearance or general operation thereof.

Various changes in the specific form shown and described may be made withinthe scope of the claims without departing from the spirit of the invention.

1 claim 1. An electro-magnetic coil comprising a core, a wire conductor arranged about said core. and a conductor element, the electrical conductivity of which varies in accordance with changes in light to which said coil is exposed, said conductor element being located externally about and in insulated convolute relation to said wire conductor and in series therewith.

2. An electro-magnetic coil comprising a core, a wire conductor of fixed electrical conductivity arranged about said core, a cover of insulating material enclosing said wire conductor, and a conductor strand, the electrical conductivity of which varies in accordance with changes in light to which said coil is exposed, extending exteriorly about said insulating cover and connected in series with said wire conductor.

3. An electro-magnetic coil comprising a core, a wire conductor of fixed electrical conductivity arranged about said core, a cover of insulating material enclosing said wire conductor, and a second wire conductor, the electrical conductivity of which varies in accordance with changes in light to which said coil is exposed, wound externally about said insulating cover and connected in series with said first named conductor.

4. A light-sensitive control system comprising an element to be controlled, an electric controlling circuit for controlling said element, a switching means in said circuit, an electro-magnetic coil arranged to operate said switching means, and light sensitive means carried by said coil in external convolute relation thereto and connected in series with said coil whereby said electro-magnetic coil is energized in accordance with variations in light to which said coil is exposed.

5. A light-sensitive control system comprising an electric lamp, an electric circuit for supplying current to said lamp, contacts constituting terminals in said circuit, an armature lever carrying one of said contacts, an electro-magnet co-operating with said armature lever to control said circuit, and a wire conductor, the electrical conductivity of which varies in accordance with changes in light, externally surrounding said coil in insulated relation thereto and connected in series with said coil. whereby said electromagnet is energized in accordance with variations in the light to which said coil is exposed.

In testimony whereof I have hereunto set my hand.

ROBERT H. STEVENS. 

